Millions of users all over the world are using virtual assistants like Alexa or Siri to help them with everything, from finding files in their computer to control smart home appliances.

When you give a command, the diaphragm, a part of the microphone will receive your voice’s sound waves and then move. After that, electrical signals will be produced, the ones the assistant’s software can understand.

It is proven that hackers do not need to give the assistants voice commands to control them

That is what we believe happens on the inside of smart home devices. Recently, research with the funding of the U.S. Defense Advanced Research Projects Agency revealed that bad actors can activate virtual assistants like Alexa and Siri without saying anything. All they need is a line of sight.

A team of experts from Michigan and Japan can control the assistant with a beam of light containing a command. What they do next is to shine the light on the microphone of the assistant. The diaphragm will move just like when it is hit by sound waves.

They could even control the device placed in a building when standing on a bell tower 70 meters away by shining the light through the window

In some tests, the team found out that they could keep a distance of 110 meters and the method still works. They could even control the device placed in a building when standing on a bell tower 70 meters away by shining the light through the window.

The equipment needed for this hacking method is available for less than $400, as stated by the researchers. If you want to use the telephoto lens, you might have to pay $600. However, that is just a small investment compared to the prospect that hackers can get all of a user’s information, from their accounts online to a way to unlock their homes.